Dec., 1948
RINGOPENING OF ACYLCYCLOHEXANONES TO e - A c n CAPROIC ACIDS
Anal. Calcd. for C ~ H ~ N Z O neut. Z: equiv., 224. Found: neut. equiv., 225.
Summary 1. The recently developed method for the preparation of ketones from aliphatic nitriles and aromatic Grignard reagents has been adapted to the preparation of ketones which may be used as
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M2X
intermediates in the synthesis of potential antimalarial or antitubercular drugs. 2. The mild method of reduction employing zinc dust and acetic acid has been adapted to the reduction of certain oximes to diamines. 3. A number of new intermediates and certain hew quinacrine analogs have been synthesized. DURHAM, N. C.
RECEIVED AUGUST2, 1948
CHEMISTRY DEPARTMENT, DUKEUNIVERSITY]
Alkaline Cleavage of Unsymmetrical p-Diketones. Ring Opening of Acylcylohexanones to Form €-Acyl Caproic Acids BY CHARLESR. HAUSER,FREDERIC W. SWAMER AND BETTYI. RINGLER There is e v i d e n ~ e ~that v ~ - the ~ cleavage of P-diketones by aqueous alkali to give carboxylic acids and ketones is concerned with the ketonic form (I) rather than with the enolic form (11) or with the anion (111) into which both (I) and (11) are first largely converted reversibly.
0
RC--B
- 0-
//
+
OH-
I I
c\
OH
RCyo
\OH
+ B--RC/
0
\O-
4- BH
Since the relative yields of the possible acids, RCOOH and R’ R’COOH, from the cleavage of an OHunsymmetrical 0-diketone (1) would !--+ or depend on the relative rates of reaction of the two carbonyl groups with R,COO- + CHtCOR hydroxyl ion, a direct relationship I11 J might b e expected between theie Perhaps the best evidence for the cleavage of (I) yields and the relative rates of alkaline hydrolysis and is that CY, a-disubstituted 0-diketones, which can- of the corresponding ethyl esters, RCOOCZHF, not be enolized or ionized, undergo alkaline cleav- R‘COOCZHB, respectively. Actually such a relaage much more rapidly than the unsubstituted tionship can be deduced from the results obtained compounds4 and that the relative yields of the two by earlier workers with certain substituted diben,~ and possible acids from the cleavage of p-chloro, p- zoylmethanes, such as P - m e t h ~ x yp-chloroP,3 bromo and p-methoxydibenzoylmethanes are ap- p-nitro2 dibenzoylmethanes, and with benzoylproximately the same as those from the corre- acetone.’ In each case the acid whose ethyl ester sponding mono-methylated P-diketones, the enoli- undergoes alkaline hydrolysis the more readily is zation of which appears to be almost completely obtained in the greater yield.8 However, the relas ~ p p r e s s e d . ~Since the cleavage amounts to a tionship fails with o-chlorodibenzoylmethane,g~lo A direct relationship might also be expected bereverse Claisen condensation, it is presumably initiated by the attack of hydroxyl ion a t the ear- tween the relative yields of the p-substituted benbony1 carbon. The mechanism for the cleavage2 zoic acids produced on the cleavage of a series of and also that for the alkaline hydrolysis of ester^,^ p-substituted dibenzoylmethanes or of a series of the relationship to which is considered below, may p-substituted benzoylacetones and the relative be illustrated b:y the following general equation in rates of alkaline hydrolysis of the corresponding which B represents CHZCOR’ or OR’, respec- ethyl esters. In these cases the R group in both (I) and equation (1) is varied while the R‘ group ti vely . 0-H
+O
I I/ R-C=CH--C-
0
)
I/ I1 RC-CH2-C-R’
1
0
RCOO-
(1) Reported a t the Chicago Meetings of the American Chemical Society, September, 1946, and April, 1948. (2) Bradley and Robinson, J . Chem. SOC.,129, 2356 (1926). (3) Bickel, THISJOURNAL, 67, 2204 (1945). ( 4 ) Kutz and Adkins, ibid., 62, 4391 (1930). (5) See Hammett, “Physical Organic Chemistry,’’ McGraw-Hill Book Co , Kew York, N. Y., 1940, p. 354. (6) It is possible that, with certain p-diketones which have fixed enolic structures, the enolic form or its anion is cleaved. See Fieser, THISJOURNAL, 81, 940 (1929). It is also possible t h a t even with certain ordinary p-dliketones the enolic form is cleaved, but, if so, the carbonyl group would presumably be involved (see Beckham and Adkins, ibid., 66, 1119 (1934)). the mechanism being represented bv eqnation (1) i n which R ie CH=C(OH)R
+ CH~COR’ two
(7) Adkins and Kutz, ibid., 62, 4036 (1930). (8) Bradley and Robinson (ref. 2) have pointed out t h a t the reiative yields of the two possible acids from substituted dibenzoylmethanes are in general related directly to the strengths of the acids However, this relationship fails with benzoylacetone (see ref. 7) (9) Bickel, THISJOURNAL, 68, 865 (1946). (10) The failure of the relationship with the ortho substituted dibenzoylmethane is not surprising since steric factors should be e v e cially operative in such cases and these factors might affect the rates of cleavage of &diketones and of the alkaline hydrolysis of esters to considerably different degrees. Even with the para-substituted dibenzoylmethanes, the relationship is only qualitative; of course a quantitative relationship could hardly be expected as the two types of reactions have been c a r r i d out under different conditions
CHARLESR. HAUSER,FREDERICK W. SWAMER AND BETTYI. RINGLER
4024
in (I) and the B group in equation (1) is kept constant as c,& or CH) and CH&OCd&, or CH2COCHs, respectively. Actually this “series” relationship has been realized. In Table I are given the yields of para-substituted benzoic acids obtained by ‘earlier workers from para-substituted dibenzoylmethanes and by us from para-substituted benzoylacetones, together with the rates of alkaline hydrolysis of the corresponding ethyl esters. In both series the yields of the para-substituted benzoic acids increase as the rates of alkaline hydrolysis of the corresponding ethyl esters increase.11 Also, as with the $-substituted dibenzoylniethanes, the relative yields of p-substituted benzoic acids and acetic acid (estimated by difference) from the cleavage of each of the p-substituted benzoylacetones (Table I) are related directly to the relative rates of alkaline hydrolysis of the two corresponding ethyl esters. However, neither the relationship involving the yields of the two possib:le acids from a particular 0-diketone, nor the “series” relationship appears to hold very well with purely aliphatic P-diket~nes.~ We have found that, on alkaline cleavage, caproylacetone and lauroylacetone form mainly caproic and lauric acids although the ethyl esters of these acids might be expected to undergo alkaline hydrolysis less readily than ethyl acetate. TABLE I ALKALJNECLEAVAGE O F P-XCeH~COCHzCOCeHs AND P-SC&IbCOCH?COCH3 % Yields of p-XCsH4COOH from j-XCoHap-XCeH4COCH2COCsHs COCHzCOCHs
X
104~“
1.15 13 ... 15 2.51 ... 28 6.21 (5.50) CjOb 36 23.7 c1 8lC 78 567 (720) KO* Rate constant (liters per mole sec.) for alkaline hydrolysis of these ethyl esters in 85% ethanol a t 25”. From Hammett, “Physical Organic Chemistry,” McGrawHill Book Co., New York, N. Y . , p. 121. See ref. 3. See ref. 2. CHzO CHI H
4P
*
Ring Cleavage.-Acylcyclohexanones may undergo alkaline cleavage either a t the acyl group or a t the ring carbonyl group. Cleavage a t the lattler position involves ring opening to form e-acyl ‘caproicacids. 0
0
I’
6
‘kk Earlier workers have reported such ring cleavages (11) It seems possible that this “series” relationship might be realized even with certain ortho-para-substituted dibenzoylmethanes or p-X-GHdCOCH1such as p-X-l2sHL!OCH~COCsH4-CHa-o COC~HI-CI-o if the ortho-substituted group is kept constant and the para-substituent is varied.
Vol. 70
with benzoyl12 and acetyl13 cyclohexanones but no yields were given.14 We have effected these ring cleavages and also those with propionyl and anisoyl-cyclohexanones in satisfactory yields. Our results are summarized in Table 11. As might be expected, the yield of e-anisoylcaproic acid was somewhat higher than that of ebenzoylcaproic acid and the yield of e-propionylcaproic acid was somewhat higher than that of e-acetylcaproic acid when the reactions were carried out under the same conditions. However, when the reaction was carried out on a 0.5 mole scale the yield for eacetylcaproic acid was improved considerably, although that for ebenzoylcaproic acid was not. Also, the corresponding cleavage of benzoylcyclohexanone with sodium methoxide in absolute methanol to form methyl e-benzoylcaproate has been effected in good yield. Since the acyl- and aroylcyclohexanones are readily prepared by the acylation or aroylation of cyclohexanone, 15,l 6 the present method for the preparation of these acyl and aroyl caproic acids appears to be more convenient than those described previously. 17,18 TABLE I1 ALKALINE CLEAVAGE OF RCO-CYCLOHEXANONES RCO(CHz)aCOOH
Yield, R
%
OC.
Neutral equiv. Mm. Calcd. Found
CH3 46 (60”) B. 160-162 4 b 158.1 157.5 CzHj 60 B. 150-151 2’ 172.1 171.5 220.3 220.6 CEH5 70e M. 84-85d 250.3 249.7 P-CH3OCeHj 9 ( J M. 129-130 a Obtained on a 0.5 mole scale. See ref. 13. Blaise See ref. 12. and Koehler, Comfit. rend., 148,490 (1909). e The yield was the same when the reaction was carried out on the 0.5 mole scale a t reflux temperature or on the 0.15 mole scale a t room temperature.
Similarly, a-acetylcyclopentanone, on alkaline cleavage, undergoes ring opening to form &acetylvaleric acid. Under similar conditions, ring opening occurred to a greater extent with the acetylcyclopentanone than with the acetylcyclohexanone. In contrast to benzoylcyclohexanone, benzoyltetralone and benzoylhydrindone undergo alkaline cleavage largely a t the benzoyl group to form benzoic acid and the corresponding ketone. (12) Bauer, A n n . chim.p h y s . , [91 1, 393 (1914). (13) Leser, Compl. rend., 141, 1032 (1905). (14) Bauer (ref. 12) reports a 50% yield of e-benzoylcaproic acid from benzoyl chloride and sodiocyclohexanone, by alkaline cleavage of the crude intermediate. However, in an attempt to reproduce this result, we have obtained only a poor yield of the acid. (15) Levine, Conroy, Adams and Hauser, THIS JOURNAL, 67, 1510 (1946). (16) Hauser. Kingler, Swamer and Thompson, ibid., 69, 2649 (1947). (17) (a) Auger, A n n . chim., [6] 2 2 , 360 (l891), (b) Etaix, ibid., [7] 9, 391 (1896); (c) Hill, THISJOURNAL, 54, 4105 (1932); (d) Plant and Tomlinson, J. Chem. Soc., 1092 (1935); (e) Billmann and I n d i a n a Acad. Sct., 54, 101 (1945), C. A , , 40, 1826 Travis, PIOC. (1946). (18) The recently developed method of Papa, Schwenk and Han69, 3018 (1947)) for preparation of o-aroyl kin (THIS JOURNAL, carboxylic acids employing the Friedel-Crafts reaction with esteracid chlorides of dibasic acids, might also be convenient for the preparation of certain €-aroyl caproic acids.
Dec., 1948
RINGOPENINGOF ACYLCYCLOHEXANONES TO €-ACYL CAPROIC ACIDS
4025
with two 100 ml. portions of ether to remove the ketone, then heated on the steam-bath to remove dissolved ether. p-Nitroacetophenone was prepared from p-nitrobenzoyl The resulting aqueous solution of the sodium salts of p-subchloride and malonic ester as described previously.zo stituted benzoic acid and acetic acid was acidified with Employing this rnethod pnethoxyacetophenone (b. p. hydrochloric acid and made up to a volume of 200 ml. with 150-152' (25 mm.))zl was obtained in 87% yield from water. After standing twenty-four hours a t room temp-methoxybenzoyl chloride and malonic ester. Cyclo- perature, the precipitated acid was filtered through a pentanone was prepared according to the method described weighed, sintered glass filter plate, washed with a little in "Organic Syntheses."22 Phenyl anisate (m. p. 73and dried to constant weight in a desiccator. A 74')z3 was prepared by Mr. D. F. Thompson of this Labo- water, correction was applied for the solubility of the acid. In ratory from anisoyl chloride and phenol according to the the case of benzoylacetone, the benzoic acid was extracted general method described previously .24 from the acid solution with two 100-ml. portions of ether, Preparation of 8-Diketones.-Benzoylcyclohexanone, the ether removed, and the solid dried to constant weight benzoyltetralone and benzoylhydrindone were prepared by in a desiccator. The p-substituted benzoic acids obbenzoylation of the corresponding ketones with phenyl bentained in this manner were essentially pure, having the zoate by means of sodium amide as described previously.% melting points reported in the literature. The yields are Employing this same general procedure anisoylcyclohexa- given in Table I. none (m. p. 114-116') was prepared in 46% yield from Cleavage of a-Acyl and Aroylcyclohexanones and Rephenyl anisate and cyclohexanone. lated p-Diketones.-The diketone (0.15 mole) was disAnal. Calcd. for Cl4H16O3: C, 72.37; H, 6.94. solved in cold 5% sodium hydroxide solution ( l O S r , excess) Found: C, 72.30; H, 6.77. and the resulting solution refluxed for one and a half hours. The remainder of the p-diketones used in this work have The solution was cooled in an ice-bath and the ketone was been prepared by acylation of the appropriate ketones with removed by extraction with ether. In the case of acetylacetic anhydride (or propionic anhydride) by means of and propionyl cyclohexanones the aqueous phase was made boron trifluoride. p-Nitrobenzoylacetone was prepared acid with concd. hydrochloric acid, saturated with salt, and as described previously.z6 Benzoylacetone (m. p. 60-61 ; the desired eacylcaproic acid was extracted with ether. yield 507-0),27 p-rnethylbenzoylacetone (b. p. 154155 (14 The ether extract was dried over drierite,, the ether remm.), yield 6270),= p-methoxybenzoylacetone (m. p. 53moved, and the residue distilled through a 10-cm. Vigreux 54, yield 25%jS Ib-chlorobenzoylacetone (m. p. 72-73'), column. In the case of benzoyl and anisoyl cyclohexaacetylcyclohexanone (b. p. 96-97 (10 mm.), yield 35%),27 nones, the aqueous solution of the sodium salt, after repropionylcyclohexanotle (b . p . 123-12.5 (20 mm .j , yield moval of the ketone, was heated on the steam-bath to re35%),27and acetylcyclopentauone (b. p. 71 -73 (8 mm.), move dissolved ether, then made acid with concd. hydroyield 337,) 3O were prepared according to a modification of a chloric acid. The precipitated acid was filtered off and repreviously described procedure.26 After saturation with crystallized from dilute ethanol. The yields and physical boron fluoride the mixture was stirred for one or two hours constants of the products from acyl and aroyl cyclohexaa t room temperature. The complex was then hydrolyzed nones are given in Table 11. by pouring into sodium acetate solutionz6and refluxing the Acetylcyclopentanone was cleaved according to the promixture for thirty minutes. The mixture was cooled to cedure used for the acylcyclohexanones. The B-acetylroom temperature and extracted with two 150-ml. portions valeric acid (b. p. 147-149 (3 mm.), neut. equiv., calcd. of ligroin (30-60";i. The ligroin extract was washed with 144.1, found 144.2) was obtained in yield of 56%. saturated sodium bicarboiiate solution until free of acetic Caproylacetone, on cleavage according to this same proacid, then with a little water, and dried over drierite. The cedure gave a (39% yield of caproic acid, b. p. 140-142 (99 ligroin was removi-d OII a stedin-bath and the residue was nim.), neut. equiv. calcd. 116.2, found 115.8. Corredistilled or recrystallized. The p-chlorobenzoylacetone is spondingly, lauroylacetone gave 65% of lauric acid, b. p. described here for the first time. 170-171 (12 mm.), neut. equiv. calcd. 200.16, found 203.0. Anal. Calcd. for CIuH30zC1: C, (il.06; I f , 4.61; C1, Alcoholysis of Benzoylcyclohexanone with Sodium 18.05. Found: C:, 61.10; 13, 4.45; C1, 18.00. Methoxide.-Clean-cut sodium (2.5 g., 0.1 mole 10%) Cleavage of @-Substituted Benzoy1acetones.-The di- was dissolved in 100 ml. of absolute methanol and 20.2 g. (0.1 mole) of benzoylcyelohexanone was added. The soluketone (0.01 mole) was weighed into a 125-ml. Erlenmeyer flask and dissolved in 80 ml. of 1% aqueous sodium hy- tion was refluxed on a steam-bath for a period of five hours. droxide. The resulting solution was kept in an oven a t The reaction mixture was cooled in an ice-bath and dry 38" for a period of five days. At the end of this period no hydrogen chloride was passed in until the mixture was just precipitate formed when a portion of the solution was satu- neutral. The precipitated sodium chloride was filtered and rated with carbon dioside, and the solution gave no enol washed with ether, the washings being added to the filtratc. Most of the methanol was removed by heating on a test with ferric chloride. The hydrolysate was extracted steam-bath under aspirator vacuum. Fifty ml. of ether (19) Analyses are hy Oakwold Laboratories, Alexandria, Virginia. was added to the residue to precipitate all remaining sodium 68, 1386 (1946). (20) Walker and Hauser, THISJOURNAL, chloride. The product was filtered, the salt washed with (21) Klages and Lickroth, Bey., 32,1.559 (1899), give 152-154' (26 ether, washings were added to the filtrate, and the resultmm.), for this compound. ing ether solution of the ester was dried over drierite. The (22) "Organic Syntheses," Coll. Vol. I, Ed. by Gilman and ether was removed on a steam-bath and the residue was Blatt, John Wiley and Sons, Inc., New York, N . Y . , p. 192. distilled under reduced pressure. There was obtained a (23) Nencki, German Patent, 46,756; Friedlander, "Fortschritte 4.7 g. forecut, consisting mainly of cyclohexanone and der Teerfarbenfabrication," 2, 137 gives m. p. 75-76'. methyl benzoate, and 14.0 g. (60%) of methyl e-benzoyl(24) Baumgarten, Walker and Hauser, THISJOURNAL, 66, 303 caproate, b. p. 200-206 (17 mm.).31 A small amount of (1944). thc ester was saponified in 20% sodium hydroxide to the ( 2 5 ) Hauser, Kingler, Swamer and Thompson, ibid., 69, e-benzoylcaproic acid, m. p. 84-85'. 2649 (1947). Cleavage of Benzoyltetralone and Benzoylhydrindone .(26) Walker and Hauser, ibid., 68, 2742 (19-46). The cleavage was carried out according to the method of (27) Adams and Hauser, ibid., 67, 284 (1945). Johnson.32 To 80 ml. of 1% sodium hydroxide solution (28) Meerwein and Vossen, J. prakl. Chem., 141, 149 (1943). was added 1.2 g. of the diketone. The mixture was steam (29) This diketone has been prepared by Dr. H. G. Walker in'this distilled until the drops of distillate were clear. Enough Laboratory by the acetylation of anisole with excess acetic anhydride alcohol was added to the heated distillate to render the globin the presence of boron trifluoride. The results will soon be pubules of oil soluble. Semicarbazide hydrochloride (1.0 8.) lished. and 1 g. of sodium acetate were added. On cooling, the
E~perirnental'~
+
(30) Blaise and Koehler, Compt. rend., 148, 1402 (1909). The diketone forms a grey-gteen copper salt which decomposes without melting at about 240'.
____
(31) Bauer, A n n . chim. p h r s . . [9] 1, 403 (1914). 66, 1317 (1943). (32) Johnson, THISJOURNAL,
4026
WALTERM. KUTZ,J. E. NICKELS,J. J. MCGOVERN AND B. €3. CORSON
semicarbazone of tetralone precipitated as white crystals (87%). The homogeneous alkaline residue, on acidification, precipita:ed benzoic acid, rn. p. 119-120°, mixed m. p. 119-120 . In the case of benzoylhydrindone the diketone was iiot so soluble, however, and after 300 rnl. of distillate had been collected, the undissolved diketone was filtered and weighed. The sernicarbazone (77%) melted a t 230-231’ (reported m. p. 233°).a3 Acidification of the alkaline residue gave a 10% yield of a compound melting at 88-89’ after recrystallization from alcohol, and which is presumed to be 1-benzoyl-2-(2-carboxyphenyl)-ethane.
Summary 1. The relative yields of the two possible acids (33) Huntress and Mulliken, “Identification of Pure Organic Compounds.” John W l e y and Sons, Inc., New York, N. Y.,1941, p. 361.
Vol. 70
and the relative yields of the series of para-substituted benzoic acids from the alkaline cleavage of para-substituted dibenzoylmethanes and para-substituted benzoylacetones have been related to the relative rates of alkaline hydrolysis of the corresponding ethyl esters. 2. Certain e-acyl and e-aroyl caproic acids have been prepared in satisfactory yield by the alkaline cleavage, involving ring opening, of aacyl and a-aroyl cyclohexanones. Similarly, 6acetylvaleric acid has been obtained from a-acetylcyclopentanone. DURHAM,NORTHCAROLINA KECEIVEI)d v c u s r 2, 1948
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Catalytic Alkylation of Indan and Tetralin by Olefins, Alcohols and Diethyl Ether BY WALTERM. KUTZ,J. E. NICKELS,J. J. ~ I C G O V E R AND N B. B. CORSON This paper describes the alkylation of indan and structure of an organic compound involves the tetralin by olefins, alcohols and diethyl ether in the assumption that the sample contains only one presence of typical alkylation catalysts. The al- species, and the acceptance of a minor yield of a kylation of tetralin by cyclopentene and cyclohex- known derivative as indicative of the structure of enel in the presence of aluminum chloride, and by the original compound. Boiling point is often acethylene2 with phosphoric acid as catalyst has cepted as criterion of homogeneity without proof been reported; the alkylation of both indan3 and that the possible mixture is separable by the distillation employed. In the case of an acknowltetralin4 is claimed in patents. The catalysts employed in the present work edged isomer mixture, the unjustified assumption were alumina-silica, “solid phosphoric acid,” is often tacitly made that the original isomer aluminum chloride, sulfuric acid and hydrogen composition is preserved in the derivative, regardfluoride-continuous operation with the first two less of yield. We have attempted to avoid these catalysts a.nd batch operation with the last three. suppositions. The isomeric compositions of the monoalkylinIndan and tetralin underwent extensive condensation reactions under the influence of alu- dan mixtures obtained in the present study were mina,-silica and aluminum chloride. The high established by the ultraviolet absorption spectra boiling products contained condensed ring systems of the mixed benzenetricarboxylic acids produced as evidenced by their high refractive indices. This by permanganate oxidation. Inasmuch as the new condensation reaction of indan is being average yield of acid was 8070, the isomer composition of the mixed acids was fairly representative studied. Monoalkyl indans and monoalkyltetralins can of the isomer composition of the antecedent hydroexist in two isomeric forms depending upon the carbon mixture. The composition of the monoallocation of the alkyl group with respect to the cy- kyltetralins could not be established in similar cloparaffinic ring. All the monoalkylated prod- manner because of poor oxidation yields. For ucts obtained in this investigation were isomer example, a fifty-fifty mixture of 5- and 6-isopromixtures, and the isomer distribution in the mix- pyltetralins gave a 25% yield of mixed acids contures depended upon the catalyst and/or condi- taining C;O(/y, of hemirnellitic acid and 20% of tritions. For example, isopropylation of tetralin a t mellitic acid. The isomer compositions of the 5’ with concentrated sulfuric acid yielded ap- monoalkyltetralins were established by the ultraproximately equal amounts of the 3- and 6-isomers, violet and infrared absorption spectra of the monoalkylnaphthalenes obtained by sulfur dehydrowhereas isopropylation a t 300’ over alumina-silica genation of the alkyltetralins !also hv the melting produced mainly the ti-isomer. The conventional method of establishing the point of the picrate in the case of the t-butylnaphthalenes). Spectroscopic technique is ideally (1) Pokrovskaya and Suschik, J. Gm. Chcm. (U.S. 5’. R.),9, 2291 (1939); Pokrovskaya and Stephantseva, i b i d . , 9, 1953 (1939). suitable for the analysis of isomer mixtures, a task (2) Ipatieff, Pines and Komarewsky, Ind. Eng. Chem., 28, 222 which is usually difficult and often impossible by (1936). conventional methods. (3) German Patent 80,158 (1895). (4) U. S. Patents 1,667,214 (1928); reissue 17,548 (1928); Incidentally, the statement of Tsukervanik and 1,741,472 (1929); 1,766,344 (1930). Terent‘eva6 that 1-monoalkylnaphthalenes are (5) Schroeter (Beu., 67, 1990 (1924)) reported t h a t aluminum chloride converted tetralin into a variety of products including anthratenc. hydrogenated phenanthrene and ditetralyl.
(6) Tsukervanik and Terent’eva, J Gcn 637 (1937)
nrm (U S. S. R ) 7
